This invention relates generally to submicron switching devices and more specifically to a nanomechanical switch using a deformable cantilever element.
A significant factor in the electronic revolution has been the steady to evolution of increasingly smaller integrated circuit geometries for the fabrication of semiconductor switching transistors. Typical feature sizes have been reduced from tens of microns in the early eighties, to roughly ten microns in the mid eighties, to below one micron in the mid nineties, until minimal lateral feature sizes of as small as 0.15 microns are not uncommon today. In addition to the obvious advantage of allowing for more transistors on a single chip, the smaller device geometries require less operating power and provide for faster switching speeds.
The preferred technology for state of the art submicron semiconductor devices is metal oxide silicon (MOS) transistors, which devices have historically allowed for ready scaling to smaller sizes as new submicron fabrication technologies are developed. MOS technology is approaching practical scaling limits, however, and it is projected that conventional MOS transistors cannot be scaled beyond 0.07 micrometers in their minimum feature size. These practical limitations include well known semiconductor phenomena, such as hot electron injection, gate oxide tunneling, short channel effects, and sub-threshold leakage that arise when the features of the transistor are too close together to allow proper turn-on and turn-off behavior.
It is also essential in military and space applications of digital electronics to prevent ambient nuclear or solar radiation from affecting the dynamic operation of switching devices. Switches based on semiconductor materials are vulnerable to such radiation effects, however.
Therefore, a need exists for a submicron switching device that does not consume excessive power, that has a fast switching response time, and that can be scaled beyond the current practical limitations for semiconductor switching transistors. The need also exists for a submicron switching device that is largely unaffected by high doses of particle, electromagnetic or other radiation.
In one aspect, the present invention provides a nanomechanical switch comprising a substrate and first, second and third electrodes formed on the substrate. The third electrode includes a cantilever member extending over the first and second electrodes. A voltage source is coupled between the first and third electrodes, wherein the cantilever member has an undeflected state when no bias is applied between the first and third electrodes, and a deflected state when a bias is applied between the first and third electrodes.
In other aspects, the invention provides for logical circuits formed of one or more such nanomechanical switches being connected together. In another aspect, the present invention provides for an integrated circuit comprising a substrate, a power conductor, a ground conductor, an input terminal and a logic circuit. The logic circuit comprises a plurality of nanomechanical switches, at least one nanomechanical switch being coupled to said power conductor, and at least one nanomechanical switch being coupled to said ground conductor. Each such nanomechanical switches comprise a first electrode, a second electrode, and a third electrode having a cantilever member extending substantially parallel to the substrate and extending over the first and second electrodes. The logic circuit further comprises a voltage source coupled between the first and second electrodes, wherein the cantilever member has an undeflected state when no bias is applied between the first and third electrodes, and a deflected state when a bias is applied between the first and second electrodes.